Methods and apparatus for material control system interface

ABSTRACT

Methods and apparatus are provided for managing movement of small lots between processing tools within an electronic device manufacturing facility. In some embodiments, a number of priority lots to be processed is determined and an equivalent number of carrier storage locations are reserved at a substrate loading station of a processing tool. The number of reserved carrier storage locations are made available either by processing and advancing occupying non-priority lots and/or moving unprocessed occupying non-priority lots from the substrate loading station. Priority lots are then transferred to the reserved carrier storage locations. Other embodiments are provided.

The present application is a continuation of and claims priority to U.S.patent application Ser. No. 11/067,311, filed Feb. 25, 2005, whichclaims priority to U.S. Provisional Patent Application Ser. No.60/548,588, filed Feb. 28, 2004. The contents of the above-identifiedpatent applications are hereby incorporated by reference herein in theirentirety.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is related to the following commonly-assigned,co-pending U.S. patent applications, each of which is herebyincorporated by reference herein in its entirety:

U.S. patent application Ser. No. 11/067,302, filed Feb. 25, 2005 andtitled “METHODS AND APPARATUS FOR ENHANCED OPERATION OF SUBSTRATECARRIER HANDLERS” (Attorney Docket No. 8812/P1);

U.S. patent application Ser. No. 11/067,460, filed Feb. 25, 2005 andtitled “METHODS AND APPARATUS FOR TRANSFERRING A SUBSTRATE CARRIERWITHIN AN ELECTRONIC DEVICE MANUFACTURING FACILITY” (Attorney Docket No.9142);

U.S. patent application Ser. No. 11/067,303, filed Feb. 25, 2005 andtitled “METHODS AND APPARATUS FOR ELECTRONIC DEVICE MANUFACTURING SYSTEMMONITORING AND CONTROL” (Attorney Docket No. 9144);

U.S. patent application Ser. No. 10/650,310, filed Aug. 28, 2003 andtitled “SYSTEM FOR TRANSPORTING SUBSTRATE CARRIERS” (Attorney Docket No.6900);

U.S. patent application Ser. No. 10/764,982, filed Jan. 26, 2004 andtitled “METHODS AND APPARATUS FOR TRANSPORTING SUBSTRATE CARRIERS”(Attorney Docket No. 7163);

U.S. patent application Ser. No. 10/650,480, filed Aug. 28, 2003 andtitled “SUBSTRATE CARRIER HANDLER THAT UNLOADS SUBSTRATE CARRIERSDIRECTLY FROM A MOVING CONVEYOR” (Attorney Docket No. 7676); and

U.S. patent application Ser. No. 10/987,955, filed Nov. 12, 2004 andtitled “BREAK-AWAY POSITIONING CONVEYOR MOUNT FOR ACCOMMODATING CONVEYORBELT BENDS” (Attorney Docket No. 8611).

FIELD OF THE INVENTION

The present invention relates generally to electronic device fabricationsystems, and is more particularly concerned with transferring substratecarriers between transport systems and processing tools within afabrication facility.

BACKGROUND OF THE INVENTION

Manufacturing of electronic devices typically involves performing asequence of procedures with respect to a substrate such as a siliconsubstrate, a glass plate, etc. (Such substrates may also be referred toas wafers, whether patterned or unpatterned.) These steps may includepolishing, deposition, etching, photolithography, heat treatment, and soforth. Usually a number of different processing steps may be performedin a single processing system or “tool” which includes a plurality ofprocessing chambers. However, it is generally the case that otherprocesses are required to be performed at other processing locationswithin a fabrication facility, and it is accordingly necessary thatsubstrates be transported within the fabrication facility from oneprocessing location to another. Depending upon the type of electronicdevice to be manufactured, there may be a relatively large number ofprocessing steps required to be performed at many different processinglocations within the fabrication facility.

It is conventional to transport substrates from one processing locationto another within substrate carriers such as sealed pods, cassettes,containers and so forth. It is also conventional to employ automatedsubstrate carrier transport devices, such as automatic guided vehicles,overhead transport systems, substrate carrier handling robots, etc., tomove substrate carriers from location to location within the fabricationfacility or to transfer substrate carriers from or to a substratecarrier transport device.

For an individual substrate, the total fabrication process, fromformation or receipt of the virgin substrate to cutting of semiconductordevices from the finished substrate, may require an elapsed time that ismeasured in weeks or months. In a typical fabrication facility, a largenumber of substrates may accordingly be present at any given time as“work in progress” (WIP). The substrates present in the fabricationfacility as WIP may represent a very large investment of workingcapital, which tends to increase the per substrate manufacturing cost.It may therefore be desirable to reduce the amount of WIP for a givensubstrate throughput for the fabrication facility. To do so, the totalelapsed time for processing each substrate should be reduced.

SUMMARY OF THE INVENTION

In a first aspect of the invention, a method is provided in which thenumber of priority lots to be processed is determined, an equivalentnumber of carrier storage locations are reserved at a substrate loadingstation of a processing tool, the number of reserved carrier storagelocations are made available, and priority lots are transferred to thereserved carrier storage locations.

In a second aspect of the invention, an apparatus is provided in which asubstrate loading station including a controller and a memory includinginstructions to be executed by the controller is adapted to determine anumber of priority lots to be processed, reserve an equivalent number ofcarrier storage locations at a substrate loading station of a processingtool, make the number of reserved carrier storage locations available,and transfer priority lots to the reserved carrier storage locations.

In a third aspect of the invention, a system is provided that includes afirst substrate loading station having a first processing tool and aplurality of carrier storage locations, a second substrate loadingstation having a second processing tool and a plurality of carrierstorage locations, a transport system for moving carriers between thefirst and second loading stations, and a manufacturing execution system.The manufacturing execution system is operative to determine a number ofpriority lots to be processed, reserve a number of carrier storagelocations at each of the first and second substrate loading stationswherein the number of carrier storage locations is based on the numberof priority lots, make the number of reserved carrier storage locationsavailable at each of the first and second substrate loading stations,and transfer priority lots to the reserved carrier storage locations atthe first substrate loading station.

Other features and aspects of the present invention will become morefully apparent from the following detailed description of exemplaryembodiments, the appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram depicting an example of a control system foran electronic device manufacturing facility according to someembodiments of the present invention.

FIG. 2 is a schematic diagram depicting an example of an electronicdevice manufacturing facility according to some embodiments of thepresent invention.

FIG. 3 is a front elevational view depicting an example of a carrierhandler according to some embodiments of the present invention.

FIG. 4 is a flowchart depicting an example process for managing prioritylots in a transport system according to some embodiments of the presentinvention.

FIG. 5 is a schematic diagram depicting example operation of anelectronic device manufacturing facility according to some embodimentsof the present invention.

DETAILED DESCRIPTION

The present invention provides methods and apparatus for expeditingprocessing of substrate lots identified as priority lots. The featuresof the present invention are particularly advantageous with the use ofsingle or small lot size substrate carriers. As used herein, the term“small lot size” substrate carrier or “small lot” carrier may refer to acarrier that is adapted to hold fewer substrates than a conventional“large lot size” carrier which typically holds thirteen or twenty-fivesubstrates. As an example, a small lot size carrier may be adapted tohold five or less substrates. In some embodiments, other small lot sizecarriers may be employed (e.g., small lot size carriers that hold one,two, three, four or more than five substrates, but less than that of alarge lot size carrier). In general, each small lot size carrier mayhold too few substrates for human transport of carriers to be viablewithin an electronic device or other manufacturing facility.

A substrate loading station that serves a processing tool may includeinternal carrier storage locations proximate to a port of the processingtool. In operation it may be desirable to have the next lot ofsubstrates to be processed either in carriers held in internal carrierstorage locations or in a carrier ready to be transferred directly fromthe transport system to the port. In a system operating at near maximumcapacity, the availability of internal carrier storage locations withina substrate loading station may be limited. The present inventionprovides methods and apparatus wherein internal carrier storagelocations may be reserved for carriers containing priority lots.Carriers containing non-priority lots may be removed from the reservedlocations either by transferring the non-priority lots to alternatestorage locations or by processing the non-priority lots and moving theprocessed non-priority lots to non-reserved storage locations in asubstrate loading station at a next processing tool. As the reservedinternal storage locations become available, carriers containingpriority substrate lots may be transferred into the reserved internalstorage locations.

An electronic device manufacturing or fabrication facility (Fab) may usean overhead transport system (OHT system) that includes a plurality ofcarrier supports or “cradles” coupled to a continuously moving conveyorsystem adapted to transfer one or more substrate carriers about thefacility. More specifically, the moving conveyor system may include aband and a plurality of drive motors coupled thereto, which are adaptedto move the band.

Further, such a facility may include tools or composite tools adapted toprocess a substrate during electronic device manufacturing. Eachprocessing tool may be coupled to a respective substrate loading stationincluding a carrier handler adapted to transfer a substrate carrierbetween the tool and the moving conveyor system. More specifically, eachprocessing tool may be coupled to a respective carrier handler adaptedto transfer a substrate carrier between a load port of the processingtool and a carrier support coupled to the band of the continuouslymoving conveyor system. In this manner, a substrate carrier may betransferred about the facility.

In addition, a transport system may include a control system adapted tocommunicate with and control operation of the moving conveyor system anda plurality of carrier handlers such that substrate carriers may bemoved to where they are needed. Turning to FIG. 1, a control system 100may include a host or material control system (MCS) 102 that is intwo-way communication with loading station software (LSS) 104 a-fexecuting on each of the controllers of each of the plurality of carrierhandlers housed in and/or under the control of substrate loadingstations. The host may include a manufacturing execution system (MES)that directs the operations of the MCS. The MCS 102 may also be intwo-way communication with a transport system controller (TSC) 106 thatmaintains the operation of the transport system including drive motorsand the conveyor. In some embodiments, each of the LSS 104 a-f nodes maycommunicate with the TSC 106 to directly exchange information regardingthe status of the transport system. These components and their operationare described in more detail below with respect to FIG. 2.

Turning to FIG. 2, a schematic diagram is provided depicting an exampleembodiment of a physical arrangement of an example Fab 201 that isespecially well suited for using small lot size substrate carriers, suchas substrate carriers that hold a single substrate or fewer thantwenty-five substrates. The depicted Fab 201 includes a high-speedtransport system with several features that make it particularlysuitable for using small lot carriers including: a high-speed, lowmaintenance, constantly moving conveyor system; a carrierloading/unloading function that does not require stopping or slowing theconveyor; a conveyor that is able to physically support many carriers atone time; a flexible conveyor that may be readily customized to adesired transport path; and control software adapted to efficientlymanage transport and transfers between process tools. These features aredescribed further below.

Previously incorporated U.S. patent application Ser. No. 10/650,310,filed Aug. 28, 2003 and titled “System For Transporting SubstrateCarriers” (Attorney Docket No. 6900), discloses a substrate carriertransport system or similar delivery system that includes a conveyor forsubstrate carriers that is intended to be constantly in motion duringoperation of the Fab which it serves. The constantly moving conveyor isintended to facilitate transportation of substrates within the Fab so asto reduce the total “dwell” time of each substrate in the Fab.

To operate a Fab in this manner, methods and apparatus may be providedfor unloading substrate carriers from the conveyor, and for loadingsubstrate carriers onto the conveyor, while the conveyor is in motion.Previously incorporated U.S. patent application Ser. No. 10/650,480,filed Aug. 28, 2003 and titled “Substrate Carrier Handler That UnloadsSubstrate Carriers Directly From a Moving Conveyor” (Attorney Docket No.7676), discloses a substrate carrier handler at a substrate loadingstation or “loading station” that may perform such loading/unloadingoperations with respect to a moving conveyor.

Turning to FIG. 3, a substrate loading station 300 equipped with acarrier handler 302 may include a controller 304, a horizontal guide 306that is moveable vertically along a frame 307 or rails, and an endeffector 308 that is moveable horizontally along the horizontal guide306. Other configurations (e.g., a robot that can move in more than twodimensions) for moving the end effector 308 to execute transfers may beemployed. A carrier handler 302/substrate loading station 300 mayfurther include internal storage locations 310 or shelves/hangers fortemporarily storing substrate carriers 312. In addition, ports 314 forloading substrates into process tools (not shown) may be accessible tothe carrier handler 302 or be part of a substrate loading station 300housing a carrier handler 300.

The controller 304 may be implemented using a field programmable gatearray (FPGA) or other similar device. In some embodiments, discretecomponents may be used to implement the controller 304. The controller304 may be adapted to control and/or monitor the operation of thesubstrate loading station 300 and one or more of various electrical andmechanical components and systems of the substrate loading station 300which are described herein. The controller 304 may be adapted to executeloading station software as indicated above. In some embodiments, thecontroller 304 may be any suitable computer or computer system, or mayinclude any number of computers or computer systems.

In some embodiments, the controller 304 may be or may include anycomponents or devices which are typically used by, or used in connectionwith, a computer or computer system. Although not explicitly pictured inFIG. 3, the controller 304 may include one or more central processingunits, read only memory (ROM) devices and/or a random access memory(RAM) devices. The controller 304 may also include input devices such asa keyboard and/or a mouse or other pointing device, and output devicessuch as a printer or other device via which data and/or information maybe obtained, and/or a display device such as a monitor for displayinginformation to a user or operator. The controller 304 may also include atransmitter and/or a receiver such as a LAN adapter or communicationsport for facilitating communication with other system components and/orin a network environment, one or more databases for storing anyappropriate data and/or information, one or more programs or sets ofinstructions for executing methods of the present invention, and/or anyother computer components or systems, including any peripheral devices.

According to some embodiments of the present invention, instructions ofa program (e.g., controller software) may be read into a memory of thecontroller 304 from another medium, such as from a ROM device to a RAMdevice or from a LAN adapter to a RAM device. Execution of sequences ofthe instructions in the program may cause the controller 304 to performone or more of the process steps described herein. In alternativeembodiments, hard-wired circuitry or integrated circuits may be used inplace of, or in combination with, software instructions forimplementation of the processes of the present invention. Thus,embodiments of the present invention are not limited to any specificcombination of hardware, firmware, and/or software. The memory may storethe software for the controller which may be adapted to execute thesoftware program, and thereby operate in accordance with the presentinvention, and particularly in accordance with the methods described indetail below. Portions of the present invention may be embodied as aprogram developed using an object oriented language that allows themodeling of complex systems with modular objects to create abstractionsthat are representative of real world, physical objects and theirinterrelationships. However, it would be understood by one of ordinaryskill in the art that the invention as described herein can beimplemented in many different ways using a wide range of programmingtechniques as well as general purpose hardware sub-systems or dedicatedcontrollers.

The program may be stored in a compressed, uncompiled and/or encryptedformat. The program furthermore may include program elements that may begenerally useful, such as an operating system, a database managementsystem and device drivers for allowing the controller to interface withcomputer peripheral devices and other equipment/components. Appropriategeneral purpose program elements are known to those skilled in the art,and need not be described in detail herein.

As indicated above, the controller 304 may generate, receive, and/orstore databases including data related to carrier locations, commandqueues, actual and/or estimated command execution times, and/or internalstorage locations. As will be understood by those skilled in the art,the schematic illustrations and accompanying descriptions of thestructures and relationships presented herein are merely exemplaryarrangements. Any number of other arrangements may be employed besidesthose suggested by the illustrations provided.

In operation, to unload a substrate carrier 312 from a transport system316 that includes a moving conveyor that transfers substrate carriers312 (also referred to as a “substrate carrier conveyor” 316) and thatpasses by the carrier handler 302, the end effector 308 is movedhorizontally at a velocity that substantially matches the velocity ofthe substrate carrier 312 as it is being transported by the substratecarrier conveyor 316 (e.g., by substantially matching substrate carrierspeed in a horizontal direction). In addition, the end effector 308 maybe maintained in a position adjacent the substrate carrier 312 as thesubstrate carrier 312 is being transported. The end effector 308 thusmay substantially match a position of the substrate carrier 312 whilesubstantially matching a velocity of the substrate carrier 312.Likewise, conveyor position and/or velocity may be substantiallymatched.

While the end effector 308 substantially matches the substrate carrier'svelocity (and/or position), the end effector 308 is raised so that theend effector 308 contacts the substrate carrier 312 and disengages thesubstrate carrier 312 from the substrate carrier conveyor 316. Asubstrate carrier 312 similarly may be loaded onto the moving substratecarrier conveyor 316 by substantially matching end effector 308 andconveyor velocities (and/or positions) during loading. In at least oneembodiment, such substrate carrier handoffs between the end effector 308and substrate carrier conveyor 316 are performed at a substantially zerovelocity and/or acceleration difference between the end effector 308 andthe substrate carrier conveyor 316.

Previously incorporated U.S. patent application Ser. No. 10/764,982,filed Jan. 26, 2004 and titled “Methods and Apparatus for TransportingSubstrate Carriers” (Attorney Docket No. 7163), describes a conveyorsystem that may be employed with the above-described substrate carriertransport system 316 and/or carrier handler 302 for transportingsubstrate carriers between one or more processing tools of a electronicdevice manufacturing facility. The conveyor system may include a ribbon(or “band”) that forms a closed loop within at least a portion of theelectronic device manufacturing facility and that transports substratecarriers therein. In one or more embodiments, the ribbon or band may beformed from stainless steel, polycarbonate, composite materials (e.g.,carbon graphite, fiberglass, etc.), steel or otherwise reinforcedpolyurethane, epoxy laminates, plastic or polymer materials that includestainless steel, fabric (e.g., carbon fiber, fiberglass, Kevlar®available from Dupont, polyethylene, steel mesh, etc.) or anotherstiffening material, etc. By orienting the ribbon so that a thickportion of the ribbon resides within a vertical plane and a thin portionof the ribbon resides within a horizontal plane, the ribbon is flexiblein the horizontal plane and rigid in the vertical plane. Such aconfiguration allows the conveyor to be constructed and implementedinexpensively. For example, the ribbon requires little material toconstruct, is easy to fabricate and, due to its verticalrigidity/strength, can support the weight of numerous substrate carrierswithout supplemental support structure (such as rollers or other similarmechanisms used in conventional, horizontally-oriented belt-typeconveyor systems). Furthermore, the conveyor system is highlycustomizable because the ribbon may be bent, bowed or otherwise shapedinto numerous configurations due to its lateral flexibility.

Turning back to FIG. 2, the example Fab 201 includes a ribbon or band203 that forms a simple loop 205 within the Fab 201. The ribbon 203 maycomprise, for example, one of the ribbons described in previouslyincorporated U.S. patent application Ser. No. 10/764,982. The ribbon 203transports substrate carriers (not shown) between processing tools 209,and comprises straight portions 211 and curved portions 213 to form the(closed) loop 205. Other number of processing tools 209 and/or loopconfigurations may be employed.

Each processing tool 209 may include a substrate carrier handler at asubstrate loading station or “loading station” 215 of the processingtool 209 for unloading a substrate carrier from or for loading asubstrate carrier onto the moving ribbon 203 of the conveyor system 207as the ribbon 203 passes by the loading station 215 (as described inpreviously incorporated U.S. patent application Ser. No. 10/650,480).For example, an end effector 308 (FIG. 3) of a loading station 215 maybe moved horizontally at a velocity that substantially matches thevelocity of the substrate carrier as it is being transported by theribbon 203, maintained in a position adjacent the substrate carrier asthe substrate carrier is being transported and raised so that the endeffector contacts the substrate carrier and disengages the substratecarrier from the conveyor system 207. A substrate carrier similarly maybe loaded onto the moving ribbon 203 by substantially matching endeffector 308 (FIG. 3) and ribbon velocities (and/or positions) duringloading.

Each loading station 215 may include one or more ports (e.g., loadports) or similar locations where substrates or substrate carriers areplaced for transfer to and/or from a processing tool 209 (e.g., one ormore docking stations, although transfer locations that do not employdocking/undocking movement may be employed). Various substrate carrierstorage locations or shelves also may be provided at each loadingstation 215 for substrate carrier buffering at a processing tool 209.

The conveyor system 207 may include a transport system controller (TSC)217 for controlling operation of the ribbon 203. For example the TSC 217may control/monitor the speed and/or status of the ribbon 203, allocatecarrier supports of the ribbon 203 that are used to support/transportsubstrate carriers, monitor the status of such carrier supports, providesuch information to each loading station 215 or the like. Likewise, eachloading station 215 may include LSS 219 for controlling carrier handleroperation (e.g., loading or unloading of substrate carriers to/from theconveyor system 207, transporting of substrate carriers to/from loadports or storage locations of the loading station 215 and/or processingtool 209 serviced by the loading station 215, etc.). A MCS 221communicates with the transport system controller 217 and the loadingstation software 219 of each substrate loading station 215 for affectingoperation of the same. The TSC 217, each LSS 219 and/or the MCS 221 mayinclude a scheduler (not shown) for controlling scheduling of theoperations performed by the TSC 217, LSS 219 and/or the MCS 221.

Process Descriptions

The system discussed above, including the hardware and softwarecomponents, are useful to perform the methods of the invention. However,it should be understood that not all of the above described componentsare necessary to perform any of the present invention's methods. Infact, in some embodiments, none of the above described system isrequired to practice the present invention's methods. The systemdescribed above is an example of a system that would be useful inpracticing the invention's methods and is especially well suited fortransferring small lot size substrate carriers, such as substratecarriers that hold a single substrate or substantially fewer thantwenty-five substrates.

In a conventional FAB operation, a lot is moved to a stocker thatservices a bay. When a processing tool load port becomes available, themanufacturing execution system is notified with a “move in request”(MIR) message (e.g., a message from a tool controller, for example, thatindicates that the tool load port is available). The MES then selectsthe next lot for processing in the tool. The lot is moved to the toolwhere processing begins. The MES is notified with a “move out request”(MOR) message once processing of the lot is complete (e.g., a messagethat indicates that the contents of a substrate carrier have beenprocessed within the tool). The MES determines what the next processstep is for the lot and stores the lot in a stocker that services thebay for, among others, the next process tool.

In a Fab equipped for single substrate and/or small lot processing,modifications to the conventional operation described above may beemployed to improve throughput of the Fab in accordance with the presentinvention. For example, in some embodiments, when processing of a smalllot (or single substrate) is completed, the MES may determine the nextprocessing tool to which the small lot carrier is to be sent, as opposedto conventional large lot operation wherein the carrier would be sent toa buffer stocker to await being requested by the next processing tool.This is because in embodiments of the present invention, the MES isaware that the substrate loading station is equipped with internalstorage locations and able to stage lots for the associated processingtool.

In another example, buffer stockers may be used by the MCS and/orsubstrate loading station as an alternate storage location. The MCS mayinclude a list of alternate storage locations. In some embodiments, thelist of alternate storage locations may be configurable by an operator.In alternative and additional embodiments, an algorithm implemented as aprogram may be used to select a preferred storage location from the listbased upon a location's available storage capacity and/or proximity tothe substrate loading station that requested the carrier be moved to analternate storage location. In some embodiments, carriers stored inalternate storage locations may be moved automatically by the MCS to thesubstrate loading station that requested the carrier be moved to analternate storage location as internal storage becomes available. Suchcarriers may be moved in an order based upon a priority of theindividual carriers that reflects how soon the substrate loading stationcan use the carriers.

Referring to FIG. 4, a flowchart is depicted that represents somespecific example embodiments of the present invention that may beperformed using the systems described above. It must be understood thatthe particular arrangement of elements in the flowchart of FIG. 4, aswell as the number and order of example steps of various methodsdiscussed herein, is not meant to imply a fixed order, sequence,quantity, and/or timing to the steps; embodiments of the presentinvention can be practiced in any order, sequence, and/or timing that ispracticable.

In the text that follows, method steps will be discussed in detail. Notethat not all of these steps are required to perform the methods of thepresent invention and that additional and/or alternative steps are alsodiscussed below. Also note that the general steps depicted in theflowcharts represent features of only some of the embodiments of thepresent invention and that they may be re-ordered, combined and/orsubdivided in any number of different ways so that methods of thepresent invention include more or fewer actual steps. For example, insome embodiments many additional steps may be added to update andmaintain databases described below, but as indicated, it is notnecessary to use such databases in all embodiments of the invention. Inother words, the methods of the present invention may contain any numberof steps that are practicable to implement the several differentinventive processes described herein.

As indicated above, the MCS 221 is responsible for delivery and storageof carriers in a bay, by sending commands to various equipment, whichinclude substrate loading stations/carrier handlers and transferstations (equipment that may perform conveyor band to band transfers,not shown herein). In some embodiments, certain aspects of the carrierhandler may me implemented in conformance with an industry standardentitled the SEMI E88-1103 standard “Specification for AMHS Storage SEM(Stocker SEM)”, which in particular details standardized commands andprotocols for control of compliant devices. Likewise, a transport systemcontroller (TSC) 117, which is responsible for controlling conveyoroperation, may be implemented in conformance with the SEMI E82-0703standard “Specification for Interbay/Intrabay AMHS SEM (IBSEM)”.Interactions with a tool's port may me implemented in conformance withthe SEMI E84-0703 standard “Specification for Enhanced Carrier HandoffParallel I/O Interface” and handling of carriers may be implemented inconformance with the SEMI E87-0703 standard “Specification for CarrierManagement (CMS)”. These four standards are published by theSemiconductor Equipment and Materials International (SEMI) industrycoalition group of San Jose, Calif. (www.semi.org) and are herebyincorporated herein by reference for all purposes.

Turning to FIG. 4, a flowchart depicting an example process 400 formanaging priority lots in a transport system is provided. The process400 begins at step 402. In step 404, the number of priority lots to beprocessed is determined. In some embodiments, an operator may specify tothe MES the number of priority lots that are to receive expeditedprocessing. The MES may indicate to the MCS that the specified number ofcarriers containing the priority lots are to be processed as soon aspossible and delivered to substrate loading stations before non-prioritylots. In some embodiments, priority lots may be expedited individually(e.g., a single carrier may contain the priority lot) and step 404 maynot be required.

In step 406, the MCS may activate a priority lot processing mode anddirect each substrate loading station associated with a processing toolthat is to process the priority lot, to reserve the appropriate numberof internal carrier storage locations within the respective substrateloading station. The MCS may thus include logic (e.g., an algorithmimplemented as a program) to identify and select specific internalstorage locations within a substrate loading station that, for example,are storing carriers with substrates that can be processed quickly(e.g., relative to other carrier's substrates) and/or substrates thatwill not be processed for a long time (e.g., relative to other carrier'ssubstrates). In some embodiments, the individual substrate loadingstations may make the selection of storage locations to reserve forstorage of the priority lots.

In additional or alternative embodiments, the number of internal carrierstorage locations that are reserved may be based on the number ofpriority lots and/or the number of priority lots that are anticipated tobe present in a substrate loading station at one time. In other words,the number of reserved locations may be equal to or less than the numberof priority lots moving through the system. For example, if there arefifteen priority lots, it may be that only ten carrier storage locationsmay need to be reserved because, e.g., by the time ten priority lotcarriers have been moved into the substrate loading station's storagelocations, five priority lots may have already been processed andremoved from the substrate loading station. In some embodiments, thenumber of reserved locations may be greater than the number of prioritylots. For example, lots may be assigned different levels of priorityrelative to each other and some substrate loading stations may reserve afixed number of storage locations for higher priority lots. In someembodiments, one or more ports for a processing tool within a substrateloading station may be reserved for use with priority lots.

In step 408, the MCS and/or each of the relevant substrate loadingstations may make the respective number of reserved internal carrierstorage locations available for use with the priority lots. In someembodiments, non-priority lots occupying reserved locations may betransferred to alternate storage locations, for example, at othersubstrate loading stations or stockers associated with the transportsystem. Alternatively, or in addition, non-priority lots occupyingreserved locations may be processed by the tool served by the substrateloading station and then transferred to a non-reserved storage locationwithin a next substrate loading station serving a next processing tool.Carriers containing non-priority lots that continue to arrive at thesubstrate loading station are prevented from being stored in thereserved storage locations. Non-priority lots are either stored in anyavailable non-reserved storage locations or transferred to alternativestorage locations in other substrate loading stations or bufferstockers.

To facilitate making reserved locations available by processing andadvancing non-priority lots and/or putting non-priority lots intoalternate storage, lot selection scheduling by the MES may be modifiedfrom a conventional scheduling algorithm. The MES may store informationabout the total capacity of each substrate loading station and thenumber of carriers currently stored at each substrate loading station.From this information, the MES may determine which lots need to be movedor processed on the particular tool requiring internal storage locationsto be made available. In some embodiments, priority lots may be storedtemporarily in alternate storage locations awaiting the availability ofreserved locations and then be automatically moved to the reservedlocations as non-priority lots are removed.

In step 410, the carriers containing the priority lots may betransferred to the reserved internal carrier storage locations withinthe substrate loading station serving the processing tool to which suchcarriers are destined. In some embodiments, the priority lots may betransferred into the reserved storage locations as soon as each reservedstorage location becomes available. At this point, any newly arrivingnon-priority lots may only be transferred into the substrate loadingstation if a non-reserved internal storage location becomes available.In step 412, the process 400 completes.

Although not pictured in FIG. 4, in some embodiments, as soon asprocessing begins on the final priority lot in a processing tool, thereserved storage locations may be made available for storingnon-priority lots, either from the alternate storage locations or newlyarriving. In alternative and/or additional embodiments, as the number ofpriority lots at a substrate loading station incrementally decreasesafter each lot is processed and then moved to a next substrate loadingstation, the number of reserved storage locations may be incrementallydecreased.

In contrast to FIG. 4, FIG. 5 depicts a moment of operation of anembodiment of the present invention, operating without the use ofpriority lots. More specifically, operation of a transport system 500including a MES 502 and three substrate loading stations 504, 506, 508serving associated processing tools PT1, PT2, PT3, respectively under aheavy throughput condition is depicted. When processing of a lotcompletes on a processing tool, the MES 502 determines the next bestprocess tool for the lot. In the example, processing tool PT3 wasselected. Solid squares represent lots waiting to be processed, emptysquares represent empty storage locations, and striped squares representlots that are (or were) in alternate storage locations. Before themoment depicted in FIG. 5, the MES 502 may have sent a transfer commandto an MCS 510 to move the lot processed at processing tool PT1 toprocessing tool PT3. However, the MCS 510 may have determined thatinternal storage was not available in processing tool PT3, so the lotwas stored in alternate storage in processing tool PT2. Processing toolPT2 may have been chosen because processing tool PT2 was the firstdevice in an alternate storage list of processing tool PT3 that hadstorage capacity at the time.

The specific moment depicted in FIG. 5 shows a storage space 512 thathas become available in processing tool PT3 and a lot 514 designated forprocessing tool PT3 (previously stored in an alternate location inprocessing tool PT2) being automatically moved on the transport system500 under the direction of the MCS 510 to the available storage location512 in processing tool PT3. Because in this example, all lots have thesame priority, there are no conflicts and needed lots will be inprocessing tool PT3 when “move in requests” for the lots are issued.

The foregoing description discloses only particular embodiments of theinvention; modifications of the above disclosed methods and apparatuswhich fall within the scope of the invention will be readily apparent tothose of ordinary skill in the art. For instance, it will be understoodthat the invention also may be employed with any type of substrates suchas a silicon substrate, a glass plate, a mask, a reticule, a wafer,etc., whether patterned or unpatterned; and/or with apparatus fortransporting and/or processing such substrates.

Accordingly, while the present invention has been disclosed inconnection with specific embodiments thereof, it should be understoodthat other embodiments may fall within the spirit and scope of theinvention, as defined by the following claims.

1. A method comprising: determining a number of priority lots to beprocessed; reserving a number of carrier storage locations at asubstrate loading station of a processing tool, wherein the number ofcarrier storage locations is based on the number of priority lots;making the number of reserved carrier storage locations available; andtransferring priority lots to the reserved carrier storage locations. 2.The method of claim 1 wherein determining a number of priority lots tobe processed includes receiving a signal representative of the number ofpriority lots to be processed.
 3. The method of claim 1 whereinreserving the number of carrier storage locations at a substrate loadingstation of a processing tool includes identifying enough carrier storagelocations sufficient to store the number of priority lots to beprocessed.
 4. The method of claim 1 wherein making the number ofreserved carrier storage locations available includes processingnon-priority lots of substrates in carriers occupying the reservedcarrier storage locations.
 5. The method of claim 4 further comprisingmoving carriers containing processed lots and occupying the reservedcarrier storage locations to carrier storage locations associated with anext processing tool.
 6. The method of claim 1 wherein making the numberof reserved carrier storage locations available includes moving carriersoccupying the reserved carrier storage locations to alternate carrierstorage locations and preventing any carriers arriving at the substrateloading station, containing only non-priority lots, from occupying thereserved carrier storage locations.
 7. The method of claim 1 whereintransferring priority lots to the reserved storage locations includestransferring only priority lots to the reserved storage locations as thereserved storage locations become available.
 8. An apparatus comprising:a substrate loading station including a controller; and a memoryincluding instructions to be executed by the controller and adapted to:determine a number of priority lots to be processed; reserve a number ofcarrier storage locations at a substrate loading station of a processingtool, wherein the number of carrier storage locations is based on thenumber of priority lots; make the number of reserved carrier storagelocations available; and transfer priority lots to the reserved carrierstorage locations.
 9. The apparatus of claim 8 wherein the instructionadapted to determine a number of priority lots to be processed isfurther adapted to receive a signal representative of the number ofpriority lots to be processed.
 10. The apparatus of claim 8 wherein theinstruction adapted to reserve the number of carrier storage locationsat a substrate loading station of a processing tool is further adaptedto identify enough carrier storage locations sufficient to store thenumber of priority lots to be processed.
 11. The apparatus of claim 8wherein the instruction adapted to make the number of reserved carrierstorage locations available is further adapted to process substrates incarriers occupying the reserved carrier storage locations.
 12. Theapparatus of claim 11 further including an instruction adapted to movecarriers containing processed lots and occupying the reserved carrierstorage locations to carrier storage locations associated with a nextprocessing tool.
 13. The apparatus of claim 8 wherein the instructionadapted to make the number of reserved carrier storage locationsavailable is further adapted to move carriers occupying the reservedcarrier storage locations to alternate carrier storage locations. 14.The apparatus of claim 8 wherein the instruction adapted to transferpriority lots to the reserved storage locations is further adapted totransfer priority lots to the reserved storage locations as the reservedstorage locations become available.
 15. A system comprising: a firstsubstrate loading station having a first processing tool and a pluralityof carrier storage locations; a second substrate loading station havinga second processing tool and a plurality of carrier storage locations; atransport system for moving carriers between the first and secondloading stations; and a manufacturing execution system operative to:determine a number of priority lots to be processed, reserve a number ofcarrier storage locations at each of the first and second substrateloading stations, wherein the number of carrier storage locations isbased on the number of priority lots, make the number of reservedcarrier storage locations available at each of the first and secondsubstrate loading stations, and transfer priority lots to the reservedcarrier storage locations at the first substrate loading station. 16.The system of claim 15 wherein the manufacturing execution system isfurther operative to receive a signal representative of the number ofpriority lots to be processed in order to determine the number ofpriority lots to be processed.
 17. The system of claim 15 wherein themanufacturing execution system is further operative to identify enoughcarrier storage locations at each of the first and second substrateloading stations sufficient to store the number of priority lots to beprocessed at each processing tool in order to reserve the number ofcarrier storage locations at each of the first and second substrateloading stations.
 18. The system of claim 15 wherein the manufacturingexecution system is further operative to cause the fist and secondprocessing tools to process non-priority lots of substrates in carriersoccupying the reserved carrier storage locations in order to make thenumber of reserved carrier storage locations available at each of thefirst and second substrate loading stations.
 19. The system of claim 18further comprising moving carriers containing non-priority lots ofsubstrates processed at the fist processing tool and occupying thereserved carrier storage locations in the first substrate loadingstation to carrier storage locations in the second substrate loadingstation that are not reserved.
 20. The system of claim 15 wherein themanufacturing execution system is further operative to cause carrierscontaining non-priority lots and occupying the reserved carrier storagelocations to be moved to alternate carrier storage locations in order tomake the number of reserved carrier storage locations available at eachof the first and second substrate loading stations.